1. Field of the Invention
The present invention relates to a piezoelectric element configured of a lower electrode, a piezoelectric layer and an upper electrode; an actuator device fabricated by providing piezoelectric elements on a substrate with a vibration plate between the group of piezoelectric elements and the substrate; a liquid-jet head for ejecting droplets from nozzle orifices by use of the actuator device; and a liquid-jet apparatus.
2. Description of the Prior Art
An inkjet recording head with the following configuration has been put into practical use. In accordance with the configuration, parts respectively of pressure generating chambers communicating with nozzle orifices are constructed with a vibration plate. The nozzle orifices are those from which ink droplets are ejected. The vibration plate is distorted by piezoelectric elements, and thus ink in each of the pressure generating chambers is pressurized. Accordingly, ink droplets are ejected from each of the nozzle orifices. An inkjet recording head which is constructed, for example, in the following manner is among such inkjet recording heads. An even layer made of a piezoelectric material is formed on the entire surface of the vibration plate by use of a film-forming technique. Then, this layer made of the piezoelectric material is cut into shapes corresponding to the pressure generating chambers by the lithography method. Thereby, the piezoelectric elements are formed respectively in the pressure generating chambers in order that the piezoelectric elements can be independent from one another.
A piezoelectric element with the following type of piezoelectric layer has been among piezoelectric elements used for such inkjet recording heads. The degree of orientation of the (100) planes of the piezoelectric layer constituting the piezoelectric element is defined as being not less than 70%. (See the scope of claims and the like in Japanese Patent Gazette No. 3555682, for example).
Even though, however, the (100) planes present in the face surface of the piezoelectric layer is defined as being oriented with priority given thereto by defining the degree of orientation of the (100) planes, when the face surface of the piezoelectric layer is measured by means of the wide-angled X-ray diffraction method, only components formed perpendicularly to the substrate (the face surface of the piezoelectric layer) can be measured with regard to each of the (111) planes and the (100) planes which are tilted planes of the piezoelectric layer. This brings about a problem that how the actual orientation is can not be distinguished. In addition, the (111), (100) and (211) planes which are tilted planes of the piezoelectric layer does not only distort themselves, but also hinders the piezoelectric layer as a whole from distorting. For this reason, this brings about a problem that the piezoelectric layer including higher proportions respectively of the (111), (100) and (211) planes is poor at displacement characteristics including the amount of displacement.
Incidentally, such problems are not limited to liquid-jet recording heads typified by inkjet recording heads, but are similarly present in other types of piezoelectric elements and other types of actuator devices using piezoelectric elements.